Quick start and stop mechanism for phonograph turntables



A ril 29, 1941. L. THOMPSON 2,240,320

QUICK START AND STOP MECHANISM FOR PHQNOGRAPH TURNTABLES Filed NOV. 26, 1958 AMPLiFiER INVENTOR LlnbalnThampson.

' ATTORNEY Patented Apr. 29, 1941 QUICK START AND STOP MECHANISM FOR PHONOGRAPH TURNTABLES Lincoln Thompson, Stamford, Conn assignor to The SoundScriber Corporation, Stamford, Conn., a, corporation of Connecticut Application November 26, 1938, Serial No. 242,598

2 Claims.

This invention relates to phonographs having records of the disc type, and more particularly to a mechanism for quickly starting and stopping the rotation of the record in order to facilitate the transcription thereof by a typist.

One object of this invention is to provide a start and stop mechanism of the above nature which will be provideed with a light weight, lowinertia turntable having a friction slip clutch connection with a continuously running motor.

A further object is to provide a start and stop mechanism of the above nature employing a pivoted electromagnetic ibrake member operated by a foot-controlled switch and adapted to engage the rim of the turntable whenever it is desired to stop the record.

A still further object is to provide a device of the above nature which will be simple in con- I3 is supported by a depending shaft [5 which is driven continuously by an electric motor I6 located below the same.

In order to reproduce the messages recorded I in the grooves of the disc record l2, provision is made of an electrical pick-up member I! having a needle 13 adapted to travel within the grooves of said record. The pick-up I1 is connected by a pair of conductors l9 and 20 to an audion amplifier 2| receiving power through conductors which in turn is connected to a pair of A. C.

struction, inexpensive to manufacture, easy.to

install and manipulate, compact, ornamental in appearance, and very eificient and durable in use.

With these and other objects in view, there has been illustrated on the accompanying drawing one form in which the invention may be embodied in practice.

The single figure on the drawing represents a section taken through the turntable, the disc record, and the magnetic brake, and shows diagrammatically the remainder of the apparatus and electrical circuits. I

In receiving news messages over the telephone, by wireless, and by dictation, the communications are often recorded on phonograph disc records, which records are then replayed to reproduce the messages on a phonograph, so that a typist may typewrite them for use in the editorial department of a newspaper. The present invention is of great importance in'facilitating the quick starting and stopping of the turntable which supports the record without stopping the motor.

Referring now to the drawing, the numer l0 indicates a rotary turntable of thin light weight metal, such as aluminum. The turntable l0 preferably has a downturned flange Illa on its periphery and a relatively thick block l0b at its center.' The central block llJb is provided with an aperture lflc which is adapted to surround a vertical pin H for centering a disc record l2 which is adapted to be supported upon the turntable Ill. The centering pin H is preferably formed integral with a driving plate l3, which is connected with the block lllb by means of a slip friction clutch 14. The driving plate line conductors 26 and 21. The output of the amplifier 2| passes through a pair of conductors 28 and 29 to a loud speaker '30,- or if desired, to a pair of head phones or a telephone receiver, not shown.

In order to energize the electromagnetic brake for stopping the turntable whenever desired, a Pair of conductors 3| and 32 lead from the conductors 22 and 23, respectively, to a rectifier 33 which converts the alternating current from the line into direct current, but it will be understood that if desired this rectifier may be omitted within the spirit and scope of the invention.

A conductor 34 leads from one output terminal of the rectifier to a foot-operated switch comprising a movable contact member 35 having an upwardly extending button 36 and a pair of stationary contacts 31 and 38 adapted to be bridged by the movable contact 35 whenever the button 36 is depressed by the foot of the operator. A coiled spring 39 is located under the movable contact to automatically raise it to the normal open circuit position shown in the drawing. A

conductor 40 leads from the contact 38 to an annular electromagnetic coil 4|, which-coil is also connected to the rectifier by a conductor 42. Loosely fitted within the interior of the coil 4| is the central member of a U-shaped soft iron core 43, the horizontal lower leg 44 of which is provided with an upstanding iron brake rod 45 pivoted at 46 to the end 01: said horizontal leg 44. At the upper end of the brake rod provision is made of a cylindrical brake shoe 41, pref erably constructed of rubber and which is located in alinement with the flange Illa of the turntable II). The brake rod 45 is normally held In operation, when it is desired to .stop the rotation of the turntable It, the operator will depress the buttonji of the foot-switch with his foot, closing the circuit through the electromagnetic coil 4I,-thus'energizing the magnetic core, the upper leg of which will attract the iron brake rod and cause the brake shoe 4'! to engage the depending flange Illa 01' the turntable, and stop the rotation thereof instantly. The motor, however, will continue to rotate,--this being made possible by the friction slipping connection mentioned above.

It will be understood that the friction between the driving plate I: and the clutch H should be made small enough so that when the turntable is stopped by the brake shoe 41, the motor will not be slowed down, but will continue to rotate at full speed. At the same time the friction should be large enough to insure the instant starting of the turntable at full speed when the brake shoe is disengaged from the turntable without being retarded by the work required to move the. needle in the grooves of the disc ing from its spirit. In short, the invention includes all the modifications and embodiments coming within the scope of the following claims.

Having thus fully described the invention, what is claimed as new, and for which it is desired to secure Letters Patent, is:

1. In a phonograph, a low inertia turntable having a depending flange around its periphery, a brake shoe for eng ging said flange whenever it is desired to stop the rotation of the turntable, a spring-retracted pivotally-mounted iron rod for supporting said brake shoe, and a foot-controlled eleetromagnet for selectively attracting said iron rod for causing said brake shoe to engage said flange and stop said turntable, continuously rotating driving means, and a slipfriction clutch for connecting said driving means with said turntable, whereby the stopping of said turntable will not stop the rotation of said driving means.

2. In a phonograph, a low inertia turntable, a brake shoe for engaging said turntable whenever it is desired to stop the rotation thereof, a

spring-retracted iron rod for supporting said brake shoe, a manually-controlled electromagnet for selectively attracting said iron rod for causing said brake shoe to engage and stop said turntable, continuously rotating driving means, and a slip-friction clutch for connecting said driving means with said turntable, whereby the stopping of said turntable will not materially slow down the rotation of said driving means.

LINCOLN THOMPSON. 

